Electrooptical system and method of control



1934. c. F. JENKINS 1,984,683

ELECTROOPTICAL SYSTEM AND METHOD OF CONTROL Filed April 22, 1930 v I: g mul 7' 35' NIH Patented Dec. 18, 1934 UNITED STATES PATENT OFFICE ELECTROOPTICAL SYSTEM AND lWETHOD OF CONTROL Application April 22, 1930, Serial No. 446,220

Claims.

This invention relates to radiomovies and television receivers of the electroscopic-valve type, the subject of application Serial No. 423,021, and has for its principal object to discharge the elec- 5 troscope elements used therein.

In said application leak resistances have been used to discharge the repellent energy which keeps the valves in light obscuring position, but resistances which have conductivity enough to discharge the valve in persistence-of-vision time, e. g., one-fifteenth of a second, are wasteful of the initial charging energy, so that the energy has to be greatly enhanced above that actually required to make it operatively effective.

It would be far more desirable to leave the initial charge undisturbed on the valve for nearly the whole time, i. e., one-fifteenth of a second, and then discharge it suddenly, as done in this invention. Not only is this far more effective, but the initial charging energy may be much less. Accordingly it is one of the principal objects of the present invention to provide an electro-optical or image transmission system wherein image storing means are employed together with means for controlling the normal condition of the storing means.

Another object of the invention is to provide a method of charging and discharging image stor- 30 ing devices in successive cyclical order.

Another object of the invention relates to the method of storing an image or picture impulse for a predetermined interval, for example that corresponding to the persistency of vision, then rapidly discharging the storing device and cyclically repeating the foregoing.

A further feature relates to a television system having a so-called reproducing screen in the form of a bank of light control elements, together with means for accurately controlling said elements whereby an image may be reproduced with greater faithfulness as regards the original, and with a smaller amount of power than has heretofore been required for similar purposes.

With these and other objects in view, the invention consists of the novel method and means herein described and illustrated, and particu larly pointed out in the claims.

Referring to the drawing;

Figure 1 is a front view of the multi-cellular member; and

Figure 2 is a sectional view of the same.

In the figures, A is the cellular member; B the cells; C the commutator of the switching gear; and D a rotating contact brush arm therefor;

D a second contact brush arm mounted on the same shaft as arm D but electrically insulated therefrom, i. e., from the arm D; E is the fixed member of the electrostatic valve, and F the movable member, or light obscuring member. 5 P is a radio receiver and P an amplifier. R is a light-source and. S a condenser lens for concentrating the light from the source onto the cell bank. It will be noted that the valves in successive rows are staggered (Fig. 2) to reduce interference due to mutualelectro-static induction.

In the operation of this device the commutator brush D is rotated in synchronism with the corresponding member in the analyzer at the distant transmitting station. The incoming radio signals, amplified, are, therefore, delivered to the proper cells through the corresponding contact points of the commutator. The charged cellvalve is, in consequence, closed if that particular elementary picture area should be dark, or partially closed if the elementary area should reproduce half -tone light values.

As the picture is constantly changing, the valves should return to initial position where light follows dark through the cells. This is accomplished by discharging the valves, and is" done by draining off the charge through brush arm D and its groundwire.

The discharging arm D precedes, more or less closely ahead of, the charging arm D, and therefore, the valves are held shut continuously in those cells where dark follows dark for some time, for example, in the dark areas of the stationary positions of the picture. In the movable parts of the picture the cell valves snap open when light follows dark, because the charge on the valves is drained off promptly.

While specific apparatus and arrangements thereof are shown, it will be understood that the invention is not limited thereto, and that various changes and modifications may be made without departing from the spirit and scope of the invention.

Thus instead of using the image impulses to close or obstruct the light valves the opacity of said valves may be reduced by the incoming signal currents. This of course may be accomplished by means of the amplifier or by using the members F as reflectors instead of obstructors. 50 When the members F are thus used as reflectors the light source R may be positioned so that when the members F are in their uncharged state the minimum amount of light is reflected, while different quantities of light may be reflected as the members F are moved away from their normal position.

Broadly considered therefore, the invention relates to a method of distributing in successive cyclical order operating or charged impulses and restoring or normalizing impulses, the latter being preferably distributed in an abrupt manner, that is just before the distribution of the operating impulses.

What is claimed is:

1. In an electro-optical system an electrostatic light valve having movable valves, a distributor having an operating contact associated with each of said valves, a charging brush, and a discharging brush for said distributor.

2. An electro-optical system according to claim 1 in which the discharge brush is grounded.

3. In combination, an electrostatic light valve having movable valves, means for operating said valves in succession by signalling impulses, and other means for abruptly releasing said valves in succession by non-signalling impulses.

1. The combination of an electrostatic light valve having movable valves, a commutator hava distributing member for operating said Valves in succession, and a second distributing member for releasing said valves in succession.

'5'. The combination of a plurality of electrostatic light valves, a commutator having a brush for charging said valves, and a second brush for discharging said valves.

6'. In a television system, means for reproducing the television signals comprising a plurality of movable electrostatic light controlled elements,

means for operating said elements, means for distributing said signals to said operating means, means for retaining said elements in their operated positions aft-er operation, and means for restoring said elements just prior to a new signal impulse.

7. In a television system, a plurality of movable electrostatic light controlled devices comprising a plurality of condensers, means for operating said devices by charging said condensers, means for charging said condensers by said television signals, and means for discharging said condensers just prior to the receipt of another signalling charge.

8. In a television system, means for reproduc ing television signals comprising an electrostatic light valve having movable valves, means responsive to television signals for operating said valves, and means for releasing said valves just prior to the receipt of another charge.

9. In a television system, means for reproducing television signals comprising an electrostatic light valve having movable valves normally in one position, means responsive to television signals for operating said valves, and means for abruptly restoring said valves to normal just prior to a new signal.

10. In a television system, means for reproducing television signals comprising an electrostatic light valve having movabl'e valves, means responsive to said signals for operating said valves, and means for restoring said valves abruptly.

CHARLES FRANCIS JENKINS. 

